Created attachment 166870 [details]
KCM using wp-fractional-scale

SUMMARY
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I just upgraded from Plasma 5.27 to Plasma 6.0.1 on ArchLinux. I am on Wayland (also on 5.27) and using fractional scaling (150%). On Plasma 6.0.1, the fonts look weird (using Noto Sans at 10 pt): attachment wp-fractional-scale-v1.png is a screenshot of kcm, which shows, for example, that the horizontal line of the letter 'e' (see the search field of kcm) is roughly twice as large as the top or bottom of the letter 'e', which looks weird to me. Or consider the letter 'g' in the word 'Hintergrunddienst' (below 'Sitzung' in the tree menu), where the bottom part of 'g' is too thin.

In trying to understand, what my be the cause of my problem, I came across

https://bugreports.qt.io/browse/QTBUG-113574

Since I do have the problem with the WebEngine too, I set the environment variable

QT_SCALE_FACTOR_ROUNDING_POLICY=RoundPreferFloor

Now not only the WebEngine problem is solved, but also kcm looks like before again. From this, I conclude that before upgrading, the wp-fractional-scale-v1-extension was not used.

I am wondering if this is a won't fix. If so, I am a  bit underwhelmed with the performance of 'wp-fractional-scale-v1'. Or is there another option that I need to set?